This invention relates to improvement in a sea to fresh water converting system or a desalinazation apparatus utilizing solar energy.
From energy conserving point of view, various desalinazation apparatus utilizing solar energy have been proposed so far. Most of these desalinazation apparatus are of the type in which sea water is heated to 100.degree. C. or more by solar energy and led to the evaporator of the apparatus. Even before then, a number of desalinazation apparatus using fossil fuel as a heating source, have been known in which sea water is also heated to a very high temperature and led to the evaporator. In these conventional apparatus, such expensive materials as cupronickel, aluminium-alloy, brass and titanium were used to withstand the bad corrosion of the pipes due to the sea water which passes therethrough at a temperature over 100.degree. C. For larger models of the desalinazation apparatus, cost of the pipes accounts for 30-55% of the entire construction fee, therefore the heat transferring pipes take up a large amount of the fee. It is thus desired to use an economical pipe material that is corrosion resistant with less resource problems. As the desalinazation apparatus utilizing solar energy is usually of a large scale, pipes leading the sea water to a solar energy collector and from there the heated sea water to the evaporator, what is called a collector circuit, would be considerably long and this fact would pose a considerable problem.
It is therefore a main object of the invention to solve such technical and financial problems involved in the installation of the heat transferring pipes for the solar energy desalinazation apparatus. For this end, first of all, oil is used as a heat transferring medium for the collector circuit, thereby avoiding the use of the conventional expensive materials and also eliminating technical difficulties by development of piping joint, taking into consideration the corrosion caused by hot sea water. In order to compensate for the decrease of thermal efficiency due to the use of oil, use is made of a bubble disturbance effect to take advantage of thermal transfer acceleration, if necessary, thereby increasing the thermal efficiency and offering an improved sea water to fresh water converting system.